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Bringing it in for a smoke test on the intake tract if they can get it in today, got a video on my phone of the noise that I will put up later and a couple data logs. Hopefully it's all just paranoia, but better safe than sorry.

Side 2 part question-The ethanol free gas we have available here is 91, might it be better to use that fuel and run a 91oct map than the 93 octane I have been using? Also the 93 octane is "tri-clean to help cut down on emissions" from citgo, might that be the reason my A/f learning numbers are screwy?

Yeah, they don't log every time I hear it, but I am logging knocks of -1.4 at least once every time I drive my car. One occurred as I heard the sound. Also pinging sounds like a good a word as any to describe what it sounds like.

Yeah, I can consistently have it make the noise in 3rd gear at about 2000 rpm by giving it maybe 25% throttle and letting off the gas. May get to about 2300 rpm max.

I think I had a similar noise after adding my AEM cai. It would come on at low rpm when letting off the throttle. Sounded like a "ping" metal sound, like 2 small wrenches lightly being tapped together. It wasn't detonation or knocking my logs were pretty much knock free. I had a smoke test done and no leaks.

It only happened at low rpm when letting off the gas, easily duplicated.

Anyway swapped out my oem BPV to a Forge and the sound was gone. In my case it was something internal with the oem BPV.

I knew it could've been the bpv! I get a small wind gust noise at those rpms/speed with my stock airbox/bpv. Putting in my Cobb SF tomorrow and I'm sure I'll have a whole new gauntlet of noises to get used to, lol.

Thanks guys, I don't have a chevron near me, but trying to look in to if I should go with the local gas place that has 91 ethanol free or go stick with the 93. Have you guys read anything about something like that?

The ethanol contents vary pretty wildly - they're supposed to be 10% ethanol blends but they really range from 5-15% depending on the day of the week, direction of the wind, etc.
In terms of energy density, gasoline is rated at ~46.4 megajoules per kilogram, whereas pure ethanol is 30 megajoules per kilogram. The net effect is that it takes around 40% more ethanol by volume to equal the amount of energy of gasoline. So realistically what that means is that the 93 octane 90/10 blend has 4% less specific energy than the 91 octane 100% gasoline blend. It's not quite as resistant to knock, but we can tune for that

Went to the dealership today for my smoke test and for the tech to check out my sound I was hearing. He pretty much told me he didn't think the sound was anything to worry about, and that they couldn't do a smoke test.

I was rather mad as the person who I scheduled with said they could, but I guess what he meant was that they could simply run the numbers and send the to Subaru to see what was wrong.

So now I have scheduled a smoke test with another auto place in town that will simply do the smoke test I have been seeking since last Tuesday!

Meanwhile I am going to post up a few of the logs I have run over the past few weeks.

Well tomorrow I SHOULD get my intake tract tested, but as everything has been going down who knows

Figured I would throw some info and two logs I took today for the hell of it. Also will put the fact out there that this week I have been running on Sunoco gas from a busy area rather than Citgo gas I get from down the street.

A/F learning looks like its changing, I was cruising no throttle at -.78 then slowly it went to +.78 then tonight it was cruising at +1.56. I will note that I have been not hesitating to take the car to boost for the past couple days as I had been the last couple of weeks which most likely will change Learning ETC.

Here are the A/F Learning Numbers after driving 1 Hour 20 Mins from work this afternoon.

@71 Degrees F Dry Clear Evening (wife was with me had to cut it short to avoid the wrath)Log from this P.M.

I know the A/F learning values are learned over periods of time and you generally monitor them over the course of 1+ tanks of gas. I simply am including this data just to be as thorough as possible with this entire post so I have it for my own records.

I see mostly slight knocks here and there within the -1.4 area with the most extreme case being a -5.6 that I saw while accelerating up a larger hill earlier today.

Some Fine Knock Learning periodically happens during acceleration in second gear as well. Other than all of this I am not noticing any loss of power and the car is not throwing any check engine light.

Perhaps this is a case where I got some bad gas from a station and need to chalk it up to learning or I will find out tomorrow that I have an intake tract leak.

Has anyone suggested putting the stock intake back on and checking the A/F trims? Cheaper than a smoke test, and if everything goes back to normal, your car obviously doesn't like the AEM intake/tune. I got the Cobb SF and airbox and put it in last Saturday and my A/F trims are almost all the same as before intake... You should ditch the AEM and try Cobb if you truly have no leak(s). Either way, I hope you get this figured out.

Also, in regards to knock, if you see events at low loads, I've read that is somewhat normal for all cars stock to protuned. As long as the wot is knock free you're good. Obviously there can still be random events at wot, but as long as they're not consistent you should be ok.

No one has suggested this, but I don't believe I can return the intake due to rallysportdirect having a no return unless unused/unopened policy. I don't really want to soak a $255 hit on my intake and buy another for around $300.

If my car comes back with no leaks I most likely will do as you said and check the numbers. If that turns out to be the case I'll look into selling the intake on here for a bit cheaper than I paid and pick up the Cobb with air box.

Just got a call back from the automotive shop that confirmed that no leaks were found during the smoke test this morning. My question is this:

How do I treat the car now and is there anything more I can do? What else to look for? I know the values are borderline and I only see small knocks occasionally and sometimes in my wot logs so I'm kind of up in the air at this point.

Most recent logs and info is in the post 3 up from this one from last night.
Any suggestions from cobb/other owners?

Switch to the 91 octane + AEM to hopefully lose the knocking completely if you keep running 93 octane. I just did this and my car feels so smooth, haven't seen any knock yet either, not even at low loads. You only lose about 1psi so power loss isn't noticeable and you give your car a 2 octane buffer. My A/F trims are almost all exactly 0 as well.

This map will also help combat overboost in winter as well. I'm going to run this map full time.